1. Field of the Invention
The present invention relates to a semiconductor laser module and a process for manufacturing the same.
2. Description of the Related Art
Semiconductor laser modules are provided with a number of components including a semiconductor laser device, a lens, a lens holder, a photodiode for monitoring output from the semiconductor laser device, a temperature controlling element and an optical isolator as disclosed, for example, in Japanese Unexamined Patent Publication (Kokai) No. Hei 10-39174. In this semiconductor laser module, light output from the semiconductor laser device is converged by the lens into a collimated beam, which is then led to an optical fiber through the optical isolator, and the beam wave-guided through the optical fiber is used for desired applications.
In such a semiconductor laser module, there are many parts, as described above, comprising a light path from the semiconductor laser device to the optical fiber, so that misalignment of optical axes is possible, particularly between the lens and the optical isolator. If such misalignment occurs in the semiconductor laser module, the light output through the lens is hampered by the optical isolator, resulting in reduced optical coupling efficiency. In addition, the semiconductor laser modules described above are expensive, since they are composed of a large number of expensive components.
It is an objective of the present invention to provide a semiconductor laser module which can not only enhance the effect of optical coupling by reducing misalignment of the optical axes between the lens and the optical isolator but also realize cost saving, and a process for manufacturing the same.
In order to attain the above objective, the semiconductor laser module, according to the present invention, for optically coupling light radiated from a semiconductor laser device to an optical fiber using a lens and an optical isolator has a constitution in which a lens holder for holding the lens is secured together with the optical isolator on a single and common securing member.
Preferably, the securing member is a channel element having a bottom plate and a pair of side walls formed on each side thereof.
Further, each side wall is preferably designed to have a length orthogonal to optical axes of the lens held by the lens holder and of the optical isolator such that the optical axis of the lens is aligned with that of the optical isolator.
Preferably, the optical isolator has a columnar shape.
Furthermore, the securing member is preferably designed to satisfy the following relationships:
W1 less than D and H1 greater than D/2xe2x88x92(D2/4xe2x88x92W12/4)xc2xd
wherein W1 represents the width W1 between two side walls; H1 represents the height of the side wall; and D represents the diameter of the optical isolator.
Meanwhile, in the case where the width between the two side walls of the securing member is substantially equal to or slightly greater than the diameter of the optical isolator, the optical isolator is disposed on the base plate between these two side walls and is welded thereto by means of YAG laser from the outside to pierce the side walls.
Further, the height of each side wall of the securing member is preferably changed between the portion where the lens holder is secured and the portion where the optical isolator is secured.
Furthermore, the lens holder is preferably secured on the securing member at a height substantially equal to that of the optical axis of the lens held by the lens holder.
Preferably, the lens holder and the optical isolator are preferably welded to the securing member.
Further, the lens holder and the optical isolator are preferably secured on tops of the side walls of the securing member.
Furthermore, the optical isolator is preferably welded to the securing member from the outside to pierce the side walls.
Preferably, the securing member is fixed on a base.
It is also preferred that the base is fixed on a temperature controlling element.
Meanwhile, in order to attain the above objective, the process for manufacturing a semiconductor laser module, according to the present invention, for optically coupling light radiated from a semiconductor laser device to an optical fiber using a lens and an optical isolator has a constitution including a step of securing a lens holder for holding the lens and the optical isolator on a single and common securing member.
These and other objects, aspects and advantages of the invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings.